Had experience with something similar on another island (Bermuda) a while back. Input all our info into their system online, had it confirmed back to us. Had it on our phones as we arrived on the island, headed for immigration, only to find that their systems were down and unable to read the data for 3 plane-loads of visitors. Growing pains, I guess, as it worked fine on a later visit. Suspect SXM will see something similar until they get the bugs out.